In general, boards are used during the manufacturing of concrete products, for example, concrete blocks, concrete curb stones, concrete sidewalk blocks, etc. Such boards are necessary products when it needs to continuously product concrete products in large quantities.
More specifically, the concrete products are manufactured in a state where the boards are disposed integral with the mold during the manufacturing of concrete products. The integrated boards and concrete product are obliged to move through a conveyor to a curing chamber, and the concrete product is cured. The substantially cured concrete product is removed. The boards separated from the concrete product can be used again. The concrete products can be continuously manufactured in large quantities in such a way that the boards circulate again in a concrete product manufacturing machinery system.
The board, which has the above-mentioned roles, can be made of wood, plastic, a material bonded with hetero materials, for example, wood, plastic, etc., and steel. Since the board made of wood or plastic may be easily impaired in its surface, it is disadvantageous that the service life of such a material may be short.
In addition, the board made of wood or plastic has a bad property for vibration transfer to the floor, which may make the density of the concrete product uneven. In case of a steel board, a vibration transfer property is good, but it is too heavy, and raw materials cost a lot, which may lead to increased manufacturing cost, so the price of the finished board may increase. The Korean Patent Registration No. 10-1195598 entitled “A board structure for manufacturing concrete products” invented by the same applicant as the present invention includes, as major components, an upper board, a lower board which is secured to the lower surface of the upper board, a space part formed in the insides of the upper board and the lower board, and a reinforcing member which is inserted in the space part.
It is advantageous that the above-mentioned configuration can make light the entire weight while enhancing structural strength of the board, but it inevitably needs to manufacture the molds for each size of the upper board and the lower board when manufacturing the board due to the intrinsic shapes of the upper board and/or lower board which is formed of an upper layer or lower layer and a bent part, so a lot of initial cost is necessary for manufacturing the boards.
In addition, a tamping work necessarily entails so as to make more tense the filled stuff of the concrete during the manufacturing of concrete products. In case of the conventional board structure, a lot of noises occurs during the tamping work.